Hydraulic valve lifter with temperature compensating lubricant metering means

ABSTRACT

An improved hydraulic valve lifter has a socket member and a body member with cooperating surfaces which define a metering passageway therebetween for metering a flow of oil to an associated rocker arm assembly. The socket member has a higher coefficient of expansion than the body member. Therefore, when the temperature of the oil and the socket member increases the socket member will expand relative to the body to decrease the cross-sectional area of the metering passageway. Since the crosssectional area of the metering passageway decreases as the temperature of the oil increases, the flow rate of the oil tends to remain constant even though the viscosity of the oil decreases.

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An improved hydraulic valve lifter has a socket member and a body memberwith cooperating surfaces which define a metering passageway therebetweeflow of oil to an associated rocker arm asse member has a highercoefficient of expansl member. Therefore, when the temperature of theoil and the socket member increases the socket member will ex tive tothe body to decrease the cross tering passageway. Since thecross-sectional area of the metering passageway decreases as thetemperature of the oil increases, the flow rate of the oil tends toremain constant even though the viscosity of the oil decreases.

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PATENTED AUG 1 01971 ME 5 m. M rm m A w W r N E w w w H 2 .6 El

HYDRAULIC VALVE LIFTER WITH TEMPERATURE COMPENSATING LUBRICANT METERINGMEANS The present invention relates to a hydraulic valve lifter, andmore particularly to a hydraulic valve lifter which is operable to metera flow of lubricant from the hydraulic valve lifter to the rocker armassembly of an internal combustion engine.

Known hydraulic valve lifters are provided with metering means forcontrolling the flow of lubricant from the lifter to a rocker armassembly. Such lifters are exemplified by the lifters disclosed in LinePat. No. 3,476,093 and in the Abell Pat. No. 3,448,730 both assigned tothe same assignee as the present invention.

Known lifters include a metering fluid passageway through whichlubricating fluid flows to the rocker arm assembly. The valve liftershave been constructed so that the cross sectional area of the meteringpassageway remains substantially constant with temperature changes. As aresult, as temperature increases there is a greater flow of lubricatingfluid through the metering passageway due to decreased viscosity of thefluid. This results in a variable flow of lubricating fluid withtemperature changes. As a result, in the known lifters, there isfrequently either too great a flow of fluid from the lifter at hightemperatures, or too little a flow of fluid at low temperatures.

In accordance with the present invention, the flow passageway throughwhich the lubricating fluid flows varies in cross-sectional dimensionupon temperature changes. At low temperatures, the flow passageway is ofits greatest size and the flow passageway decreases in size as thetemperature increases. Accordingly, the flow passageway cross-sectionalarea changes, namely, decreases, as the viscosity of the fluidincreases. As a result, the flow of fluid through the meteringpassageway can be maintained substantially constant. In accordance withthe present invention, the change in the crosssectional area of themetering passageway is effected by manufacturing the parts defining thepassageway of materials having difl'erent coefficients of expansion.

Accordingly, the principal object of the present invention is to providea new and improved hydraulic valve lifter having a metering passagewaythrough which fluid for lubricating a rocker arm assembly flows, andwherein the cross-sectional area of the metering passageway iscontrolled with changes in temperature so as to provide for asubstantially constant flow of lubricating fluid to the rocker armassembly.

A further object of the present invention is to provide a new andimproved hydraulic valve lifter having a metering passageway with across-sectional area which decreases as the temperature of the valvelifter increases to thereby at least partially control the flow oflubricant to the rocker arm assembly associated with the valve lifter.

Another object of the present invention is to provide a new and improvedhydraulic valve lifter having a body member, a socket member located inthe body member, and a metering passageway defined by cooperatingsurfaces of the socket member and the body member and wherein the socketmember has a higher coefficient of expansion than the body member whichcauses the socket member to expand faster than the body member as thetemperature of the valve lifter increases to thereby effect a decreasein the cross-sectional area of the metering passageway as thetemperature of the valve lifter increases.

A further object of the present invention is to provide a new andimproved hydraulic valve lifter, as noted in the next precedingparagraph, wherein the increase in temperature of the valve lifter whicheffects the decrease in size of the metering passageway also causes adecrease in the viscosity of the fluid to be metered, and wherein thedecrease in cross-sectional area of the metering passageway compensatesfor the decrease in the viscosity of the fluid to be metered so that theflow of metered fluid through the metering passageway is substantiallyconstant.

A still further object of the present invention is to provide a new andimproved hydraulic valve lifter having a socket member having a fluidpassageway therein for directing fluid from a fluid reservoir located inthe hydraulic valve lifter, a metering passageway for metering the flowof fluid to the fluid passageway and wherein the metering passagewaydecreases in cross-sectional area as the temperature of the valve lifterincreases to thereby compensate for the decrease in viscosity of thefluid due to the increase in the temperature thereof.

Further objects and advantages of the present invention will be apparentfrom the following description of a preferred embodiment of the presentinvention made with reference to the accompanying drawings forming apart of the specification and wherein:

FIG. 1 is a schematic view of a hydraulic valve lifter and relatedassemblies in an engine block;

FIG. 2 is a cross-sectional view of a preferred embodiment of theinvention taken approximately along the lines 2-2 of FIG. 1;

FIG. 3a is an enlarged cross-sectional view of a portion of thehydraulic valve lifter illustrated in FIG. 2 showing the rela tivelylarge cross-sectional area of the metering passageway when the socketmember has a low temperature; and

FIG. 3b is a view similar to FIG. 3a but showing the relatively smallcross-sectional area of the metering passageway when the socket memberhas a high temperature.

The present invention provides an improved hydraulic valve lifter, andparticularly an improved metering means for metering the flow oflubricant or oil from the lifter to a rocker arm assembly of an internalcombustion engine. The metering means includes cooperating surfaceslocated on the socket member and valve lifter body. The cooperatingsurfaces define a metering passageway which meters the flow of lubricantfrom the valve lifter to the rocker arm assembly. The socket member isconstructed of a material having a higher coefficient of expansion thanthe material of which the body member is constructed so that an increasein temperature of the socket member and the expansion thereof effects adecrease in size of the metering passageway. The present invention maybe embodied in valve lifters of a variety of constructions and by way ofexample a hydraulic valve lifter l0, embodying the present invention, isillustrated in FIG. 1.

The hydraulic valve lifter 10 controls the movement of an engine valve20. The valve 20 controls the flow of gases into and from the combustionchamber 14 of a cylinder of the engine. The valve member 20 is movedbetween the open and closed positions with respect to a valve seat 20aby a valve gear, generally designated 21.

The valve gear 21 is actuated by a cam 9 which engages the hydrauliclifter 10. The cam 9 consists of a circular portion 11 and a raisedportion 13, which rotate with a cam shaft 12. The bottom portion of thelifter 10 engages the cam 9 which imparts motion to the lifter duringits rotation. The cam 9 rotates in a clockwise direction and an upwardmotion is imparted to the lifter 10 as the ramp 13a of the cam 9 engagesand moves relative to the lifter 10. An upward motion of the lifter If)ef fects an upward movement of the valve gear 21 and an opening of thevalve 20. When the ramp 13!; engages with and moves relative to thelifter 10, a downward movement of the lifter I0 and of the valve gear 21is effected. The downward movement of the valve gear 21 closes valve 20and it engages the valve seat 20a.

A push rod 15 is interposed between the lifter I0 and a rocker arm 17.Movement of the push rod 15 by the lifter 10 causes the rocker arm I7 topivot about bearing 18 and effect opening or closing of the valve 20.The push rod 15 has a tubular inner passageway 16 which allows lubricantto flow therethrough from the valve lifter 10 to the bearing 18 of therocker arm. When the rocker arm 17 is raised by an upward movement ofthe push rod 15 acting upon a shoulder 17a thereof, the rocker arm 17pivots about the bearing 18 and a shoulder 17b of the rocker arm 17exerts a downward force to open the valve 20. A spring 19 biases theshoulder 17b upwardly so that when the ramp 13b engages with the bottomof the lifter, the spring 19 effects an upward movement on member 30 hasa closed end 31 which is engaged by the cam 9 as shown in FIG. 1.Disposed within the hollow body member 30 are a plunger member 32 and apush rod socket member 33. Seated within the push rod socket on a pushrod seat 34 is the push rod 15. A snap ring 41 is disposed in an annulargroove 41a in the portion 35 of the hollow body member 30 to hold theparts of the lifter within the body member 30.

The plunger member 32 at least in part defines a lubricant reservoir 40.Lubricant such as oil is pumped into a passageway 42 in the portion 35of the body member 30 by some suitable means not illustrated, such as apump. The passageway 42 communicates with an annular groove 43 in theportion 35 of the body member 30 which in turn communicates with apassageway 45 in the plunger member 32 to allow lubricant to flow intothe reservoir 40. Therefore. during normal operations the reservoir 40is filled with lubrica nt.

The reservoir 40 communicates with a lower rressure chamber 52 by meansof a passageway 46 located in the lower end of the plunger member 32.Disposed within the pressure chamber 52 is a check valve 47. The checkvalve 47 rests within a check valve retaining cup 48 suitably connectedto the plunger member 32 at the shoulder 49. The check valve 47 isbiased into engagement with a valve seat 47a formed on the lower end ofthe plunger member 32 by a spring means 50 attached to the bottom of thecheck valve retainer cup 48.

When the hollow body member 30 is moving in a downward direction, thecheck valve 47 tends to open and allow lubricant to flow from thereservoir 40 through passageway 46 into the pressure chamber 52. Thecheck valve 47 opens when the chamber 52 enlarges with a'correspondingreduction in pressure therein. The enlargement of chamber 52 is effectedby the plunger spring 51 which biases the plunger 32 away from thebottom portion 31 of the body member 30. During a downward motion of thelifter the forces acting thereon are such that the spring 51 effectsenlargement of the pressure chamber 52, as is well known. The drop inpressure in chamber 52 leaves the check valve 47 with unbalanced forcesacting thereon. The pressure acting on check valve 47 from the reservoir40 is much greater than the pressure in chamber 52 and overcomes theforce of the spring 50 and the pressure in the chamber 52 to open thecheck valve 47. When the body member 30 moves upwardly the fluidpressure in the chamber 52 is increased. The pressure increase inchamber 52 tends to push the check valve 47 against the valve seat 47a,thus sealing the pressure chamber 52 from the reservoir 40.

When the check valve 47 closes passageway 46 due to an upward movementof the body member 30, the lubricant in the pressure chamber 52 isessentially sealed therein. The lubricant sealed within the pressurechamber 52 is substantially incompressible and therefore when the hollowbody member 30 is raised, the lubricant within the pressure chamber 52will exert an upward force which resists downward movement of theplunger member 32 relative to the body member 30. As a result, theplunger member 32 moves in an upward direction, thus opening the valveas described hereinabove. During each valve opening stroke, a smallamount of lubricant trapped in the pressure chamber 52 escapes or leaksaround the plunger through a small space 60 disposed between the bodymember and the plunger member. This leakage is termed "leak-down and isnecessary in order to insure that the valve 20 can be fully seated onthe subsequent return stroke which occurs with a continued rotation ofthe cam 9. Were it not for this leak-down" during r-ach lifting strokeand any of the parts of valve train lengthened due to an increase intemperature, such greater length would hold the engine valve 20 slightlyoff its seat 20a.

The plunger member 32 is disposed to abut the socket member 33 at thebottom portion 53 thereof and the plunger return spring 51' biases theplunger into engagement with the socket 33 during normal operation.Therefore, an upward movement of the plunger member 32 causes an upwardmovement of the socket member 33. This upward movement of the socketmember causes the push rod 15 which is engaged upon the push rod seat 34of the socket member to move upwardly. The upward movement of the pushrod 15 and its opening of valve 20 has been described hereinabove.

The hydraulic lifter 10 provides for lubricant flow through the push rodpassage 16 to the rocker arm 17. To this end, the socket member 33 hasan annular peripheral surface 38 upon which is located an inlet 38a. Aradially extending passageway 37 is interposed between the inlet 38a anda perpendicular passageway 36. The passageway 36 has an outlet 36a incommunication with the push rod seat 34. Spaced from the annular groove43 is a groove 61 which includes an O-ring seal 610 which cooperateswith the body member 35 and socket member 33 to prevent the free flow oflubricant therepast. The passageways 36, 37 and the openings 38a, 36aallow lubricant to flow from the reservoir 40 through the passageways tothe passageway 16 within the push rod 15 and to the rocker arm 17.

In accordance with the present invention, the hydraulic valve lifter ll)includes means for metering the flow of lubricant from the reservoir 40through the push rod 15 and to the rocker arm 17. The meteringmeans'includes a surface 62 (FIG. 3a) of the socket member 33 and thesurface 64 of the portion 35 of the body member. The surfaces 62 and 64cooperate to define a metering passageway 66 disposed therebetween for.metering the flow of the lubricant from the reservoir 40 to thepassageway 37 in the socket member 33. The flow of lubricant is meteredby controlling the cross-sectional area of the metering passageway 66which is proportional to the difference in the outer diameter of thesocket member 33 and the inner diameter of the upper portion of the bodymember 35. By varying the outer diameter of the socket member 33 or theinner diameter of the upper portion 35 of the body member the separationbetween thesurfaces 62 and 64 can be varied thus, varying thecross-sectional area of the metering passageway 66. i

The socket member 33 is constructed of a material which has a highercoefficient of expansion then the material of which the body member isconstructed. The high coefficient of expansion of the socket member 33effects an increase in the outer diameter of the socket member 33 whenthe tem perature of the socket member is raised. Since the coefficientof expansion of the socket member 33 is higher than the coefficient ofexpansion of the body member 30, the socket member expands faster thanthe body member when the temperature of the lifter 10 is raised. Thefaster expansion of the socket member 33 causes the outer diameter ofthe socket member to increase to thereby decrease the cross-sectionalarea of the metering passageway.

It should be apparent that the temperature of the socket member 33 willvary depending upon the mode of operation of the engine within which thevalve lifter 10 is mounted. When the engine is not operating thetemperature of the socket member 33 will be relatively low. However,when the engine is started the temperature of the socket member 33 willincrease due to the friction caused by movement of the valve lifter l0and the parts therein. Further increases in the speed of operation ofthe engine and the increased friction associated therewith will cause astill further rise in the temperature of the socket member 33. As thetemperature of the socket member increases, the outer diameter of thesocket member 33 will also increase, causing a reduction in thecross-sectional area of the metering passageway 66. Thus, it should beapparent that when the engine is initially started and relatively coldthe cross-sectional area of the metering passageway 66 will be muchgreater than the cross-sectional area of the metering passageway 66after the engine has been run for a short period of time and isrelatively hot. This is a result of a high coefficient of expansion ofthe socket member 33.

Generally, the viscosity of the lubricating fluid used to' lubricate therocker arm 17 varies with the temperature of the fluid. At lowtemperatures the viscosity of the lubricating fluid is high, but as thetemperature of the fluid increases the viscosity will decrease. Thus,when the engine is cold and the lubricating fluid is relatively thick orviscous, the socket member 33 is contracted relative to the body member35 so that the metering passageway 66 is relatively large (FIG. 30).Therefore, the relatively viscous lubricating fluid can flow at adesired rate through the metering passageway to the rocker arm 17. Whenthe engine is warmed up and the lubricating fluid is relatively thin,the socket member 33 is expanded relative to the body member 35 so thatthe metering passageway 66 is relatively small (FIG. 3b). Therefore, theflow of the relatively thin, low viscosity lubricating fluid isrestricted so that the desired flow rate is not substantially exceeded.Thus, the use of materials having different coefficients of expansionenables the size of the metering passageway 66 to be varied withvariations in temperature to provide a substantially constant flow oflubricating fluid to the rocker arm 17.

The socket member 33 may be constructed of a wide range of materialswhich have a high coefficient of expansion. To this end a material suchas 18-8 stainless steel may be used. Generally, stainless or austeniticsteel expands clue to a temperature increase at approximately 150percent of the rate at which ferritic steels expand. Therefore, theutilization of a stainless steel socket member with a ferritic steelbody member will effect a decrease in the cross-sectional area of themetering passageway 66 by lessening the clearance between the outerdiameter of the socket member 33 and the inner diameter of the upperportion of the body member 30 when the temperature of the valve lifteris increased. Thus, the provision of a stainless steel socket member anda ferritic steel body member will provide for a constant flow oflubricant as disclosed hereinabove.

It should be realized that the provision of a constant flow of lubricantto the rocker arm assembly 17 is desirable in most engines. To this end,the coefficient of expansion of the socket member 33 must be chosen inview of the coefficient of expansion of the body member 30 and the typeof lubricant that is to be used in the valve lifter 10. The provision ofa socket member having a proper coefficient of expansion will allow thecross-sectional area of the metering passageway to vary as the viscosityof the lubricant varies to thereby provide a constant flow of lubricantto the rocker arm assembly.

While a preferred embodiment of the present invention illustrates aconstant flow of lubricant to the rocker arm assembly 17, it should beapparent that a nonconstant flow of lubricant could also be provided bythe utilization of a socket material having a higher coefficient ofexpansion. This may be desirable in certain situations wherein a higherflow of lubricant to the rocker arm assembly 17 is needed due to higheroperating temperatures of the engine. Therefore, it should be apparentthat the flow rate of lubricant may be controlled by the relationship ofthe coefficient of expansion of the socket member 33, the coefficient ofexpansion of the body member 30 and the characteristics of thelubricating fluid that is used to lubricate the valve train 21.

Moreover, it should be apparent that a metering members disclosed in theLine Pat. No. 3,476,093 could also be utilized in the present inventionto decrease the cross-sectional area of the metering passageway 66 whenthe temperature of the lifter increases. The metering member could bedisposed so as to meter the flow of lubricant into the passageway 37.The metering member would be constructed of a material hiving a highcoefficient of expansion so that the flow of lubricant through thesocket member would decrease as the metering member expands due to anincrease in temperature. Thus, as the temperature of the metering memberwas increased due to the friction acting on the hydraulic valve lifter10, the metering member would expand and tend to decrease the effectivecross-sectional area of the metering passageway. Clearly, as

discussed hereinabove the expansion of the metering member would occuras the viscosity of the lubricant decreased so that a constant flow oflubricant could be provided to the rocker arm assembly if it is sodesired.

From the foregoing it should be apparent that a hydraulic valve lifterhas been provided which has a metering passageway therein for meteringthe flow of lubricant from the hydraulic valve lifter to the rocker armof an internal combustion engine. The socket member and the body memberhave cooperating surfaces which define the metering passagewaytherebetween for metering the flow of lubricant. The socket member isconstructed of a material which has a higher coefficient of expansionthan the material from which the body member is constructed and themetering is provided by controlling the clearance between the outsidediameter of the socket member and the inside diameter of the bodymember. When the valve lifter and the lubricant are cold the lubricanthas a high viscosity and there exists a relatively large clearancebetween the socket member and the body member which provides a meteringpassageway having a relatively large cross-sectional area. However, asthe engine tempera ture increases and the viscosity of the lubricantdecreases, the socket expands more rapidly than does the body member sothat a decrease in the cross-sectional area of the metering passagewayis effected. Thus, a substantially constant flow of lubricant to therocker arm is provided by controlling the cross-sectional area of themetering passageway as the viscosity of the lubricant varies.

What I claim is:

1. A hydraulic valve lifter for use in a valve train including a rockerarm assembly, said hydraulic valve lifter comprising a body member madeof a material having a first coefficient of expansion, and a socketmember located at least partially within said body member and made of amaterial having a second coefficient of expansion which is greater thansaid first coefficient of expansion, said socket member having a firstfluid passageway therein for directing lubricating fluid therethrough tothe rocker arm assembly, said socket member and said body member havingcooperating surfaces which define a second fluid passageway forcontinuously metering a flow of lubricating fluid to the rocker armassembly, said socket member being expandable relative to said bodymember in response to an increase in temperature to decrease thecross-sectional area of said second fluid passageway and to therebycontrol to' at least a limited extent the flow rate of lubricating fluidto the rocker arm assembly as the temperature of the valve lifter andlubricating fluid increases.

2. A hydraulic valve lifter as defined in claim 1 wherein thecross-sectional area of said second passageway and the viscosity of thelubricating fluid varies with changes in temperature in such a mannerthat the lubricating fluid has a high viscosity and said secondpassageway has a relatively large cross-sectional area at a relativelylow temperature and the lubricating fluid has a low viscosity and saidsecond passageway has a relatively small cross-sectional area at arelatively high operating temperature.

3. A hydraulic valve lifter as defined in claim 2 wherein changes in thecross-sectional area of said second passageway with changes intemperatures are such as to provide for a substantially constant flow oflubricating fluid to the rocker arm assembly even though the viscosityof the lubricating fluid changes with changes in temperature.

1. A hydraulic valve lifter for use in a valve train including a rockerarm assembly, said hydraulic valve lifter comprising a body member madeof a material having a first coefficient of expansion, and a socketmember located at least partially within said body member and made of amaterial having a second coefficient of expansion which is greater thansaid first coefficient of expansion, said socket member having a firstfluid passageway therein for directing lubricating fluid therethrough tothe rocker arm assembly, said socket member and said body member havingcooperating surfaces which define a second fluid passageway forcontinuously metering a flow of lubricating fluid to the rocker armassembly, said socket member being expandable relative to said bodymember in response to an increase in temperature to decrease thecross-sectional area of said second fluid passageway and to therebycontrol to at least a limited extent the flow rate of lubricating fluidto the rocker arm assembly as the temperature of the valve lifter andlubricating fluid increases.
 2. A hydraulic valve lifter as defined inclaim 1 wherein the cross-sectional area of said second passageway andthe viscosity of the lubricating fluid varies with changes intemperature in such a manner that the lubricating fluid has a highviscosity and said second passageway has a relatively largecross-sectional area at a relatively low temperature and the lubricatingfluid has a low viscosity and said second passageway has a relativelysmall cross-sectional area at a relatively high operating temperature.3. A hydraulic valve lifter as defined in claim 2 wherein changes in thecross-sectional area of said second passageway with changes intemperatures are such as to provide for a substantially constant flow oflubricating fluid to the rocker arm assembly even though the viscosityof the lubricating fluid changes with changes in temperature.